Joints undergo degenerative changes for a variety of reasons. When joint degeneration becomes advanced or irreversible, it may become necessary to replace the natural joint with a prosthetic joint. Artificial implants, including hip joints, shoulder joints, and knee joints are widely used in orthopedic surgery. Specifically, hip joint prostheses are common. The human hip joint acts mechanically as a ball and socket joint, where the ball-shaped head of the femur is positioned within the socket-shaped acetabulum of the pelvis. Various degenerative diseases and injuries may require replacement of all or a portion of a hip or other joints using prosthetic implants constructed of metals, ceramics, plastics, or other synthetic materials.
A “joint revision” refers to a surgery wherein a surgeon removes an existing orthopedic implant, such as a knee or hip prosthesis, and replaces it with a revision implant. Revision surgeries may become necessary due to degeneration of bone over time or advancement of a degenerative disease. For example, bone is often lost around the rim of the acetabulum, and this may provide less rim coverage to securely place a prosthetic cup or to place bone screws.
In joint restoration and revision surgeries, the patient's anatomy surrounding the joint is severely degraded or damaged to the point where accurate navigation of the surgical instruments and proper placement of implants becomes a significant challenge that can negatively impact surgical outcomes. For example, a surgeon may be unable to locate and identify anatomical reference points that are needed to perform the surgery. It may also be difficult for the surgeon to locate and identify sensitive areas, such as blood vessels or nerves that should be avoided during surgery. For example, the surgeon may need to identify and locate portions of the patient's anatomy that are of sufficient quality to accept mechanical fasteners, such as bone screws, and thereby secure and stabilize the implant, while avoiding blood vessels, nerve, or other sensitive areas. Improved, patient-matched surgical guides that align a prosthetic implant and direct placement of fasteners to suitable areas of anatomy may help surgeons improve surgical outcomes.